The commonly used method of adjusting and checking the air chamber push rod travel is very deceiving. Most mechanics and drivers alike, may do a brake adjustment and then never really visually check the very critical item of how far the air chamber push rod actually moves when the brakes are applied. Some prior art devices designed for checking travel of air chamber push rods consist of several parts, which make them costly and time consuming to install. As they were intended to be permanently installed on the vehicle. The devices currently being used seem to have missed a very critical area concerning air brake adjustment, it is the need to visually check all brakes to be sure they are equally adjusted or balanced. This will provide a much safer and controllable stopping condition. The improper adjustment and balancing of the air brakes in the past have contributed to many accidents. It is especially dangerous on long down hills, as improperly adjusted brakes will cause more heat buildup and possible fire and failure. Those concerned with the safety of heavy duty highway vehicles will recognize the extreme importance of a tool to quickly indicate if any brake needs adjustment or repair.
It is one objective of the present invention to provide an inexpensive tool that will promote a safer braking system for heavy duty highway trucks and buses. It provides for a visual quick check of the air chamber push rod travel, so that mechanics and drivers can tell if any brake work is needed. The present invention is inexpensive, versatile and easy to use; it can be left in place on the air chamber push rod for a quick visual check of the vehicle brake adjustment and balance condition at anytime. The present invention can greatly add to the straight line stopping or staying in its own traffic lane under severe stopping conditions of heavy duty trucks and busses. All that is needed is a visual check to see if both front brakes are adjusted equally or balanced as the Department of Transportation requires.
The present invention is a tool to indicate the position of the air chamber push rod in an air brake system that is attached to the undercarriage of a vehicle. The air brake system includes an air supply, an air chamber with a movable push rod attached to a slack adjuster, then to a shaft that activates the brake shoes. Upon brake application, air is introduced into the air chamber from the air supply. This causes outward movement of the push rod from within the air chamber. This outward movement of the push rod from the air chamber is the criterium that is used by the Department of Transportation and Highway Patrol in their safety inspection. Push rod travel during brake application relates directly to brake adjustment. With the brakes un-applied, inspectors make a chalk mark on the push rod at the air chamber. Then with the brakes applied, they check the distance the push rod and chalk mark have moved away from the air chamber. Any movement over 2" is a citation. The present invention, a visual brake rod position indicator, is a plastic washer with a center hole, just slightly smaller than the air chamber push rod. It also has a wedge cut out from the outside edge to the center hole. With the wedge removed it will allow the flexing of the washer by bending the open ends in opposite directions and allowing it to be slipped of the air chamber push rod. The placement of this washer along the push rod near the air chamber, where the inspection chalk mark is normally applied will enable a mechanic, driver or inspector to tell at a glance if the brake conditions are acceptable or need attention. While the chalk mark doesn't last long, this indicating tool is very durable, easy to see and will encourage proper adjustment and maintenance of air brake systems.